Energy efficiency is increasingly becoming an important differentiator from mobile phones to datacenters. Customers are willing to pay a premium for longer lasting mobile device experiences but also are anxious to get increasing performance from these same devices. On the other end of the scale, datacenters continue to scale up compute power but face thermal limits for what can be efficiently cooled. In addition, the public is increasingly more conscious of energy usage and environmental impact of energy use. Making efficient use of energy is therefore a higher priority design goal in many types of computing systems.
As mobile devices become ubiquitous, power management and integration with the cloud become increasingly important to provide uninterrupted access and persistence of data on mobile devices. Mobile devices today typically have relatively few power states. The device is either in use operating at full power, or in a standby or idle state and operating at low power. If the battery is low, the device may take some steps to reduce power usage, such as dimming the screen. However, such actions may interfere with the user's use of the device.
Datacenters face similar issues. In some cases, an organization operates multiple datacenters and has the flexibility to route computing requests to more than one datacenter based on certain criteria. For example, the datacenter operator may be able to route only as many requests to a datacenter as the datacenter has computing and cooling capacity. The operator can then send any overflow requests to another datacenter at another location.
The decisions made in these situations are often not made optimally because they are made without using complete knowledge of the situation. For example, a datacenter may not anticipate that based on the time of day, the client requests are about to drop dramatically so that offloading work is not needed or is only temporarily needed. Likewise, a mobile device may not anticipate that the user plans to plug in the device in 10 minutes, so the existing amount of battery life, even though low, is sufficient to allow the user to use the full capabilities of the device. These decisions lead to results that are not as desirable as what could be achieved with smarter devices, or by using the comprehensive set of contextual knowledge available for the circumstances in which the devices operate.